I use Marine-Tex epoxy instead gel coat for surface repairs, But get A LOT of flack for not using polyester http://www.marinetex.com/marinetexepoxyputty.htmlI've used it to build up the bottom of my hulls, repair both bows, the leading edge of my centerboards on my H17 (an annual thing) and several significant dings (Oh, the life of a river sailor) It works great, is easy to use, file and sand. You can paint, but not gelcoat over it. For major repairs I first do the glass work in polyester (fiberglass resin and cloth) then surface coat with the Marine-Tex. Since my boat is white, the white Marine-Tex is a good match.

Hint: If you have a H17 and want to build up the leading edge of your centerboard (the edge that gets dragged on the beach) prep the surface as instructed, apply a liberal amount of epoxy along the edge, then apply blue panter tape along both sides (no wrinkles) so the tape A-frames around the bead and tape-to-tape along the upper edge. Apply even pressure on both sides to squeeze out the air and even out the putty within the tape. If carefull you get a great leadind edge that needs just a little filing and sanding.

If you use non polyester stuff... you have to keep using non polyester stuff, if you use polyester resin/gelcoat you can keep piling it on. If gelcoat were hard to work with I might suggest other epoxies, but there isn't a whole lot of difference. You have to clean you area, mix it right, apply and clean it up with sanding or whatnot. Also, how much time do you have and what is available to you?

Polyester resins are typically easier to work with than epoxies. The mixing ratios are much more forgiving and they cure more quickly.

The main problem with using epoxy on a Hobie hull is that you have to remember where you used it because you can't later go back to using polyester (unless you grind out all the epoxy). Epoxy is good for bonding, joining, and delam repairs. For laminating, surface repairs, or anywhere you need to do finish work, polyester is generally preferred.

thanks guys this is great info..i think you guys are right maybe i should do some glass work before i gel it.. ive never done any before so this is all new to me, im going to have to make a trip to west marine about 10min drive from my boat pretty handy but its still damn cold here in toronto anyone know what temperatures are okay to do glass or gel work in?

Generally speaking, somewhere in the 60 to 80 degree range is best since the reaction time is temperature dependent, outside of this range will impact curing time pretty significantly. With polyester resin, you can correct for this to some degree by varying the amount of catalyst used. With epoxy, your choice of resin will determine cure time.

Here is some helpful info regarding polyester curing times and catalyst ratios.